Rectifying apparatus



Sept. 9, 1952 s. c. COLLINS RECTIFYING APPARATUS Filed May 24, 1948 OOOOOOGOO ooooooooo :M oeooonooo 24 ooooooooe Elven-for:

Jawzuel U. UZZL'MS'.

Patented Sept. 9, 1952 RECTIFYING APPARATUS Samuel C. Collins, Watertown, Mass., assigner to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application May 24, 1948,` Serial No. 28,870

This invention relates-to rectifying; or fractionating apparatus, especially to a rectifying column of the vertically spaced tray type.

Although the invention is not necessarily limited in its application to the separation of air, it is originally and specifically applied to an air fractionating system for oxygen generation, of the so-called Linde simple or single column type, as will be well understood by those skilled in the art, and as is set forth in chapter VI of The Separation of Gases, by M. Ruhemann, Oxford University Press, 1945, rst published in 1940.

One of the chief problems in connection with fractionation is that of obtaining close contact `between liquid and vapor. The liquid tends to form in either too large particles, preventing close contact, or in too small particles, resulting in entrainment thereof with the vapor. The problem isv to obtain good contact, and at the same time effective separation of liquid and vapor and a proper balance of flow of the two phases. v

It is an object of this invention to provide an improvedA rectifying column in which the liquid and vapor `.phases are brought into close contact, with a minimum of entra-inment of the liquid phase bythe vapor phase. It is another object of this invention to provide a fractionating column in which counterfiowing vapor and liquid phases are brought into intimate contact but may still be effectively separated. These and other objects are accomplished in a rectifying or. fractionating column in which a plurality of vertically stacked trays permit a general downward ow of liquid and upward flow of vapor, but in flowing in these general directions, the liquid and vapor cross back and forthfrom one side of the column to the other. Each tray is perforated at one end to permit upward flow of vapor, and is provided with liquid passages at its `opposite end. The trays areestacked vso that the perforated ends alternate with the liquid drain ends. A baffle is associated rwith the perforated end to substantially prevent the entrainment of liquid by the upwardly moving vapor. .w y I In the drawings: i

Fig.` 1 is a vertical longitudinal section through a column embodying the invention.

Fig. 2 is a view in section on the plane of line 2- -2 of Fig. 1, and

Fig. 3 is a view in section on the plane of line 3-3 of Fig. 2.

The` rectifying or fractionating column is shown as being enclosed at the top by a cover member 2, into which liquid is introduced through a conduit II and from which vapor leaves by way of a con- `i2 claims. (o1. zen-1113 I duit E. In an oxygen generator, the vapor leaving by way of conduit 6 consists of Waste gases, mostly nitrogen. Numerous trays, indicated generally at 8, are shown as being stacked vin vertically spaced relationship, and are soldered together as at 9 toform a hermetically sealed co1- umn. The bottom tray, 8', is shown as being deeper than the trays 8 to provide space for a boiler-condenser. The boiler-condenser or tray 8 collects liquid, which in an air fractionating system is oxygen.

A coil II is disposed in the bottom of the column to complete the boiler-condenser- In an air fractionating system, air news through coil II and is condensed therein, after which it passes into the top of the column by way of an expansion I valve XP and conduit 4, as is well understood .by those skilled in the art and as is clearly brought out in Ruhemann, above.

Oxygen product may be removed from the column in either the liquid or the vapor state; in this embodiment, I have shown a liquid outlet LO.

Each tray 8 comprises a shallow elongated pan member Ill having a bottom I2 and sloping raised sides I 4. Near one end of each tray, there are provided numerous small perforations forming a perforated portion IB. At the underside of the bottom I2 of the tray, there 'is provided a baffle lilconsisting ofa flat, preferably perforated. member having'one edge 20 secured to` the pan adjacent thefinner edge of the perforated portion I 6 and extending outward beyondthe outer edge of the perforated portion. The outer edge 22 of the baille is spaced vertically from the outer edge of the pan bottomv I 2.

At the end opposite the perforated end, there is provided `one or more liquid drains 24. In the preferred form, there are several such liquid drains, as shown in Fig. 2, and they are preferably aligned along an axis normal to the long axis of the tray, again as shown in Fig. 2.

As arranged in the column the trays are spaced vertically in a nested relationship, the bottom of one tray being supported in the top of the next tray below. The trays are arranged or stacked sothat the liquid drain of one tray empties into the perforated end of the next tray below, but it should be noted that the relationship of the drains and perforations is such that the extreme outer end 26 of the tray adjacent the perforations is itself imperforate in order that the liquid drains will not empty immediately onto a perforated portion of the pan bottom. This is best seen in Fig. 1.

Asis also best seen in Fig. l, the innermost edge of the perforated portion of each tray is ciose to the end of the `tray-i. e., does not approach the middle of the tray-with the result that, in the stacked trays, there is a subsantial length of imperforate tray bottom between the inner edge of the perforated portion of one tray and the inner edge of the perforated portion of the next adjacent'tray. Thev result of this arrangement and structure is that the vapor rising in the column is not permitted to go almost straight up from one perforated portion to another, but must travel a substantial.distance horizontally as well as vertically, thusgiving-entrained droplets of liquid a chance to drop out.

Although the invention may berpracticed. witlifin rather wide variations of tray proportionsoa suggested preferred form is one in whichfthe length of the horizontal Vapor path on which gravity may act to remove entrainedMl-iqulid (i. e., the length of the tray from the inner edge .of the perforated portion to the tipofthe' baiile of the next abovef'tray-ethedimension L of Fig. 1) -is' at -least` iive times the-vertical distancev between trays (the 'dimension `H of-Fig. 1);' also the length of the horizontal vapor path, asabove defined, is preferably from oneto two timesthe width of that path (the dimension W of Fig. 2).

-In some applications oi the invention, an out- -er casing 28 may befound desirable, but itwill usuallysuiilce to stack the trays-one within another as shown, and solder them together` asy described above to Jform azhermeticallysealed eolumn.

f Operation In'operation, liquid enters/thecolumn through the'inlet conduit 4 and discharges onto'the'imperforate strip Y26 adjacent the perforated por- 'tionlt `The liquid thus discharged ontothetopmost tray ows to theleit, as seeninFig. l,

across 'the perforated portion i6 andtoward-the drains 2d at the other end of the tray,- Here the liquid `discharges-onto the'imfperiorate stripfi of the next tray below andlowsecross theV perforatedportion it of `that tray to thev right,fas seen in Fig. l, etc., downward through', the column. kSince the lowerends of drains 2id ,arelsubmerged below theliquid level, vapor is .compelled toiow upward through thel perforatedportions 'i6 of the trays, lcoming into intimate/contact with theliquid as it passes through the v.perforations.

As the lvapor Ypasses upward throughthe perforations and through the liquid which `is flowing across the perforations, it may entrain some liquid droplets with it. Suchliquid asmay ..rresult in the entrainment of some liquid by the vapor. .The relatively long horizontal path assobeV thus entrainedis separated out ofthe vapor stream by the action otgravity as .themixture ows horizontally across the tray and by Athe barile of the next'tray Yalcove as the .vapor passes aroundthe end of the baiiie in order Yto'reach the perforations of that tray. The path available to the vapor-around the end of the haiiie is such that the vapor will movel along thatpath rather than through the ne perforations in the baflie, because they perforationsin the bafes are'so small thatfthe surface-tension` of aillm of liquid across the holes'eiiectively .blocks iiow niggas therethrough. lnmoving aroundthe end of the bailie, the vapor streamis subjected tosharpvchanges of direction which cause the remaining entrained liquid to drop out. The number and sizeof perforations in the 4perforatedportion -Iof each traylis such that downward flow of liquid through the perforations is substantially prevented bythe -upward-flow of vapor therethrough.

ciated with each tray along which vapor must `i'iowfinits generaiupward movement gives gravf itya:goodiztopportunity to remove much of the entra-ine'dfliquid,and the remainder is substantially completely removed by the baiile of the next tray. y

...Whilezthere is in this application specically described'one form which the invention may as'-l su-me in practicei it.willbeunderstood thatthis lform ofthe same isxshownior purposesof illustration, and .that theY invention may `beirnodiiied and embodied in various other forms withoutdeparting fremits Yspirit 4or the scopeioi thez-appended claims.

What I claim Vas new and desireto-secure-by LettersPatentis: f

l. In a irectifying column, -a pluralty'of-vertically stacked trays, each trayfcomprising afshallowy elongated pan memberhavinga plurality of perforations through the bottom ofthe'pan-near oney end only, a haine beneathfthepanandisecured thereto adjacent the inner edge of the-perforated portion and extending-outwardbeyond vthe outer Ledge of the perforated.portionandz'a liquid drain at the ,end of "the -zpan opposite fthe .perforated end.

2. The column of claim`.l,:in whichithe trays are stacked'so thatthe liquidxdrainxof `one :tray empties into :the perforated endfof 'theneXt-.tray below.

rforated portion of a tray is horizontally'displaoed from the'. discharge. ofthe tray .nextabove siiiiciently so i thatl said. discharge empties `:ontosan 'imperforate portion of'trayhottom.

[ruin a' rectii'ying columna: apluralityzof vertically stacked trays, each tray comprising a 'shallow`elongated pan member-having a pluralityof perforationsthrough the .bottom Vof the pan -near one end only, a-bailie secured to the underside of `the pan member below the-perforationsiinthe panbottom and extending- 'outward beyondf-the outer edge of the perforated portiomand al liquid drain. at the end of the `panoppositethe baiiie lend. i

5. 'The column of claim 4, in which the baiilefis afflatcmember and lis secured by oneedge to the pan bottom near the inner edge of the perforated portion yoi therpan, the outerV edge ofthev baiile being. vertically spaced somewhatfrom the outer edge of the perforatedportion ofthe pan.

6. The column of claim 5, in which thetrays are stacked so that the liquid "dra-inof one tray 4empties into the perforated. end iof"thenextitray below. l

.7.1In a rectifying column, a `pluiaiity#offfvertically sta-cried trays, each tray comprising ashallow elongated pan member having la1 pluralityof perfcrations through the bottom of-.th'e pari, near one. end, `aperforatedlnatzmeinber .constituting a baiiie :and having its tinner.- edge secured v to 'i the panbottom Vadjacent theiinner edgefofthe perforated; pan portion, rtlieouter. edge of the-baille being vertically spaced from the outer edge of the perforated pan portion and extending outward beyond the outer edge of the perforated portion, and a liquid drain at the end of the pan opposite the perforated end.

8. The column of claim 7, in which the trays are stacked so that the liquid drain of one tray empties into the perforated end of the next tray below.

9. In a rectifying column, a plurality of vertically stacked trays, each tray comprising a shallow elongated .pan member having a perforated portion near one end immediatelyadjacent an imperforate strip, a baliie consisting of a, flat member secured by one edge to the pan bottom near the inner edge of the perforated portion, the outer edge of the baffle being vertically spaced from the outer edge of the perforated portion and extending outward beyond the outer edge of the perforated portion, and a plurality of liquid drains at the end of the pan member opposite the perforated portion, the drains being aligned along an axis normal to the long axis of the pan, the trays being stacked so that the liquid drain of one tray empties onto the imperforate strip adjacent the perforated portion of the next tray below.

10. In a rectifying column, a plurality of Ver tically stacked trays, each tray comprising a shallow elongated pan member having a plurality of perforations through the bottom of the pan near one end, a baffle member secured by one edge to the underside of the pan bottom near the inner edge of the perforated portion of the pan and extending outward beyond the outer edge of the perforated portion, and a liquid drain at the end of the pan opposite the baffle end, the trays being stacked so that the perforated ends and drain ends alternate, the trays beingl so proportioned that the length of the horizontal vapor path across the column is at least five times the vertin cal distance between trays.

il. The column of claim 10, in which the length of said path is from one to twov times its width.

12. A rectifying column as set forth in claim 9, in which the innermost edge of the perforated portion of each tray is spaced a substantial distance outward from the middle of the tray so that the stacked trays have a substantial length of imperforate tray bottom between perforated portions of adjacent trays.

SAMUEL C. COLLINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 243,197 Perin June 21, 1881 333,464 Horan Dec. 29, 1885 1,637,947 Kotzebue Aug. 2, 1927 1,748,704 Chillas Feb. 25, 1930 1,782,735 Mackenzie Nov. 25, 1930 1,950,313 Linde Mar. 6, 1934 2,055,048 Puls Sept. 22, 1936 2,116,933 Ragatz May 10, 1938 2,401,569 Koch June 4, 1946 

